Numerous factors, such as muscle strain, bad posture, prolonged sitting, heavy lifting, inactivity, obesity, vitamin deficiencies, or age-related changes to the spine such spondylosis or slipped discs, can cause lower back discomfort. Stress and bad sleeping posture can occasionally make the pain worse. Rest, stretching, frequent walking, proper posture, and avoiding heavy lifting help the majority of minor cases. You should contact a doctor for a comprehensive evaluation if the discomfort spreads to your legs and you have numbness, weakness, fever, or trouble urinating.